1. Field of the Invention
The present invention relates to a replaceable print head, and in particular to a replaceable print head for use on a printing system such as a thermal transfer printer.
2. Description of the Related Art
Stationary print heads of a type which have a print line comprising a plurality of heating resistors are commonly employed in thermal transfer printers. These devices operate by urging the heating resistors against an ink ribbon. The ink ribbon is thereby urged against the document as the document is driven across the print head assembly. Selective heating of the resistors allows the ink from the ink ribbon to be selectively transferred to the document.
Printing systems which employ a printing head, such as thermal transfer printers, have been found to be particularly troublesome with regard to replacing the print head. During the life of such printing systems, it may become necessary to replace a worn or defective print head with a new one. However, the replacement of a print head, and in particular a thermal transfer print head, has heretofore been a complicated and time-consuming procedure which often requires the help of a trained technician.
Printing systems have been known to employ replaceable print heads having four or more outwardly extending mounting pins. These systems utilize intricate mounting structures which require complicated mounting and alignment procedures in order to replace the print head.
These replacement procedures have been especially complicated in thermal transfer printers due to the fact that the print head in such printers must always maintain a tight contact with both the ink ribbon and the document to be printed in order to reduce heat resistance and to facilitate ink transfer from the ribbon onto the document. Further complications arise by the fact that a highly accurate alignment of the print head with the document and with a platen must be maintained in order to insure that even, unfluctuating printing occurs at correct locations on the document.
The procedure for replacing a print head has heretofore required complex mounting and alignment steps which often must be performed by skilled technicians employing specialized tools. Such procedures have proved to be extremely costly and inefficient. As a result, the use of thermal transfer printers has been found to be impractical in conditions where the printers are operated by persons having little or no technical training, such as with airline ticketing agencies, theater ticketing agencies and the like.
It is therefore an object of the present invention to provide a thermal transfer printing system which is practical for use in conditions such as airline ticketing, theater ticketing, and the like.
It is also an object of the present invention to provide a printing system wherein a replaceable print head can be replaced by a quick and simple procedure requiring little or no technical skills.
Another object of the present invention is to provide a printing system wherein a replaceable print head can be replaced without the use of tools.
It is further an object of the present invention to provide a printing system wherein a replaceable print head can be aligned with respect to the printing system by a quick and simple procedure requiring little or no technical skills.
It is further an object of the present invention to provide a printing system wherein a replaceable print head can be aligned with respect to the printing system without the use of tools.
It is yet a further object of the present invention to provide a printing system wherein a replaceable print head can be repeatedly and accurately aligned in a specific alignment arrangement with respect to the printing system by a quick and simple procedure.
These and other objectives are achieved in the present invention by means as will be described below.